This invention relates to a method for amplifying a solid-state laser by passing a laser beam through an amplifier several times while compensating for the thermal distortion in the laser beam by means of bending mirrors, polarizers, a Faraday rotator and a phase conjugate mirror in combination with the amplifier.
Conventionally, a laser beam is amplified by making a single pass through an amplifier (J. L. Emmett et al., Lawrence Livermore Laboratory, No. UCRL-52863, April (1980)). The conventional method of laser beam amplification is shown schematically in FIG. 1, in which the laser beam is indicated by 1 and the amplifier by 2.
The laser beam 1 emitted from the oscillator generally has low energy and the single-pass system shown in FIG. 1 is unable to exhibit a saturation behavior in amplification; therefore, the energy stored in the amplifier 2 cannot be fully extracted and only low laser output power and overall efficiency result.
An object, therefore, of the present invention is to provide an efficient method for laser beam amplification that can produce an output of high quality by employing bending mirrors, polarizers, a phase conjugate mirror, etc. in combination with the amplifier.